/*
 * Copyright 2002-2018 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.util.comparator;

import org.springframework.util.Assert;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.Comparator;
import java.util.List;

/**
 * A comparator that chains a sequence of one or more Comparators.
 *
 * <p>A compound comparator calls each Comparator in sequence until a single
 * Comparator returns a non-zero result, or the comparators are exhausted and
 * zero is returned.
 *
 * <p>This facilitates in-memory sorting similar to multi-column sorting in SQL.
 * The order of any single Comparator in the list can also be reversed.
 *
 * @param <T> the type of objects that may be compared by this comparator
 * @author Keith Donald
 * @author Juergen Hoeller
 * @since 1.2.2
 * @deprecated as of Spring Framework 5.0, in favor of the standard JDK 8
 * {@link Comparator#thenComparing(Comparator)}
 */
@Deprecated
@SuppressWarnings({"serial", "rawtypes"})
public class CompoundComparator<T> implements Comparator<T>, Serializable
{

    private final List<InvertibleComparator> comparators;


    /**
     * Construct a CompoundComparator with initially no Comparators. Clients
     * must add at least one Comparator before calling the compare method or an
     * IllegalStateException is thrown.
     */
    public CompoundComparator()
    {
        this.comparators = new ArrayList<>();
    }

    /**
     * Construct a CompoundComparator from the Comparators in the provided array.
     * <p>All Comparators will default to ascending sort order,
     * unless they are InvertibleComparators.
     *
     * @param comparators the comparators to build into a compound comparator
     * @see InvertibleComparator
     */
    @SuppressWarnings("unchecked")
    public CompoundComparator(Comparator... comparators)
    {
        Assert.notNull(comparators, "Comparators must not be null");
        this.comparators = new ArrayList<>(comparators.length);
        for (Comparator comparator : comparators)
        {
            addComparator(comparator);
        }
    }


    /**
     * Add a Comparator to the end of the chain.
     * <p>The Comparator will default to ascending sort order,
     * unless it is a InvertibleComparator.
     *
     * @param comparator the Comparator to add to the end of the chain
     * @see InvertibleComparator
     */
    @SuppressWarnings("unchecked")
    public void addComparator(Comparator<? extends T> comparator)
    {
        if (comparator instanceof InvertibleComparator)
        {
            this.comparators.add((InvertibleComparator) comparator);
        }
        else
        {
            this.comparators.add(new InvertibleComparator(comparator));
        }
    }

    /**
     * Add a Comparator to the end of the chain using the provided sort order.
     *
     * @param comparator the Comparator to add to the end of the chain
     * @param ascending  the sort order: ascending (true) or descending (false)
     */
    @SuppressWarnings("unchecked")
    public void addComparator(Comparator<? extends T> comparator, boolean ascending)
    {
        this.comparators.add(new InvertibleComparator(comparator, ascending));
    }

    /**
     * Replace the Comparator at the given index.
     * <p>The Comparator will default to ascending sort order,
     * unless it is a InvertibleComparator.
     *
     * @param index      the index of the Comparator to replace
     * @param comparator the Comparator to place at the given index
     * @see InvertibleComparator
     */
    @SuppressWarnings("unchecked")
    public void setComparator(int index, Comparator<? extends T> comparator)
    {
        if (comparator instanceof InvertibleComparator)
        {
            this.comparators.set(index, (InvertibleComparator) comparator);
        }
        else
        {
            this.comparators.set(index, new InvertibleComparator(comparator));
        }
    }

    /**
     * Replace the Comparator at the given index using the given sort order.
     *
     * @param index      the index of the Comparator to replace
     * @param comparator the Comparator to place at the given index
     * @param ascending  the sort order: ascending (true) or descending (false)
     */
    public void setComparator(int index, Comparator<T> comparator, boolean ascending)
    {
        this.comparators.set(index, new InvertibleComparator<>(comparator, ascending));
    }

    /**
     * Invert the sort order of each sort definition contained by this compound
     * comparator.
     */
    public void invertOrder()
    {
        for (InvertibleComparator comparator : this.comparators)
        {
            comparator.invertOrder();
        }
    }

    /**
     * Invert the sort order of the sort definition at the specified index.
     *
     * @param index the index of the comparator to invert
     */
    public void invertOrder(int index)
    {
        this.comparators.get(index).invertOrder();
    }

    /**
     * Change the sort order at the given index to ascending.
     *
     * @param index the index of the comparator to change
     */
    public void setAscendingOrder(int index)
    {
        this.comparators.get(index).setAscending(true);
    }

    /**
     * Change the sort order at the given index to descending sort.
     *
     * @param index the index of the comparator to change
     */
    public void setDescendingOrder(int index)
    {
        this.comparators.get(index).setAscending(false);
    }

    /**
     * Returns the number of aggregated comparators.
     */
    public int getComparatorCount()
    {
        return this.comparators.size();
    }


    @Override
    @SuppressWarnings("unchecked")
    public int compare(T o1, T o2)
    {
        Assert.state(!this.comparators.isEmpty(), "No sort definitions have been added to this CompoundComparator to compare");
        for (InvertibleComparator comparator : this.comparators)
        {
            int result = comparator.compare(o1, o2);
            if (result != 0)
            {
                return result;
            }
        }
        return 0;
    }


    @Override
    @SuppressWarnings("unchecked")
    public boolean equals(Object other)
    {
        return (this == other || (other instanceof CompoundComparator && this.comparators.equals(((CompoundComparator<T>) other).comparators)));
    }

    @Override
    public int hashCode()
    {
        return this.comparators.hashCode();
    }

    @Override
    public String toString()
    {
        return "CompoundComparator: " + this.comparators;
    }

}
